The present invention relates to typewriter locking devices, used to safeguard against damages and prevent correction ribbon feed when a typewriter is transported. Specifically, this invention concerns an integral locking device for a typewriter, having a moveable carrier, to be used during transport of the typewriter, which locks the carrier in a predetermined channel position, locks the correction ribbon bail on the carrier, and jams a correction ribbon release device.
2. Description of Related Art
Prior art teaches diverse typewriter locking devices used to safeguard against damage when a typewriter is transported. Vought et al. 1983 (U.S Pat. No. 4,403,879), teaches a complex and involved moveable carrier locking device, used to safeguard against damages when a typewriter is transported. The invention prevents shifting of the carrier at a predetermined position, by locking the carrier on a typewriter base frame. Two blades pivotally mounted on the base frame engage the underside of the carrier, thus locking the carrier in a predetermined position. The predetermined position is a point at which a sensor, and a plate on the carrier meet. The meeting allows a user to slide a switch, thereby, pivoting the blades to lock the carrier, and also shutting off electrical power to the electrically driven carrier.
Vought et al., however, is complex, involving numerous blades, points of engagement, fingers, members, mounts, and wires, as well as, involving electricity. Furthermore, the user needs to locate the predetermined position, the meeting of the sensor and the plate, before he may lock the carrier. Such a requirement may be time-consuming and frustrating. Vought et al., also does not teach a device to lock a correction bail on the carrier and/or jam a correction ribbon releasing device on the correction bail. Lastly, Vought et al.,s predetermined locking position is difficult to change as the majority of the locking mechanism is mounted on, or interact with, parts which are mounted on the base frame of the typewriter.
Garbell, 1929 (U.S. Pat. No. 1,699,061), and Rose, 1928 (U.S. Pat. No. 1,677,210), teach carriage locking devices as opposed to carrier locking devices, to protect against shocks and strains occasioned during transport. Garbell's device, also moves a rack bar off the carriage, further preventing longitudinal movement of the carriage. Garbell like Vought et al., however, teaches a relatively immutable locking position, because the actuating key member can only reside in a few areas of the keyboard. Furthermore, Garbell's device does not interact with a moveable carrier, and other devices common to modern typewriters.
Rose, like Garbell, teaches disconnecting a carriage moving mechanism in order to lock the carriage. Rose teaches a lever, which disconnects the carriage moving mechanism from the carriage, and is positioned so that, when a user covers the typewriter with a cover, the cover engages the lever. In addition, Rose teaches a moveable carriage, which can only be locked in a central position for transport, and does not address locking a correction bail.
Barron, 1900 (U.S. Pat. No. 657,153), teaches a device which locks ribbon feed after a predetermined amount of ribbon is unwound. Barron does not teach locking a correction bail. Furthermore, Barron teaches direct interaction with the ribbon, an inefficient and possibly damaging method of restraining the ribbon.
A common practice in the art is to place a rubber band over the top of a correction bail to prevent correction ribbon feed during transport. The rubber band holds down the correction bail preventing the correction bail from pivoting up and down, thereby, preventing the correction ribbon from feeding. This common practice, however, has several drawbacks. First, the rubber band is often difficult to remove from the correction bail, as one needs to reach underneath the carrier in order to stretch and pull the rubber band off the carrier and correction bail. Secondly, a rubber band sometimes loosens during transport, and therefore, cannot prevent the correction bail from pivoting up and down.
A correction ribbon feed mechanism which feeds correction ribbon in response to the correction bail pivoting up and down is disclosed in U.S. Pat. No. 4,886,383 dated Dec. 12, 1989, invented by Hans W. Mueller and assigned to Smith Corona Corporation.